Everyone hates email. Here's what could replace it.

Last summer, employees at Treehouse, a 70-person company that offers online courses in writing code and developing apps, felt workflow was frustratingly inefficient.

On the one hand, people were pushing work onto each other, so individuals were spending too much time answering colleagues and not enough on their own work. On the other, information was siloed, so if you needed some information, you were forced to bug other people to get it.

The problem? Email. Their solution? Abolish it. Well, most of it.

"Everyone was so relieved," says Treehouse CEO Ryan Carson. "We get emails from our students, so there's still the obligation to respond to those, but all the internal ridiculousness has gone away. I think people love it. I love it. And when I tell people this, they have the same reaction you do -- like, 'Oh my God, this is amazing! I hate email. How did you guys do it?'"

Although there are only a third as many business email accounts as consumer accounts -- 929 million as opposed to 2.97 billion in 2013 -- the majority of email traffic comes from the business world, according to Radicati, an email and communications research firm. On average, people receive 121 business emails a day. By 2018, that number is projected to reach 140.

"[Email] is universally available on every single device in every single country and every network. And every person has it. And that makes it a universal communications tool," says Ted Schadler, vice president and principal analyst serving chief information officers at Forrester Research. It is also widely used because it enables one-to-one, one-to-many, and group communications.

"Downsides [for the individual] are that email can be annoying. Your inbox is never empty, everything is undifferentiated, you get all your stuff in one place, from high priority to low priority," Schadler says. "For institutions, the problems are that information is hidden away. You can't search other people's mailboxes without imposing Big Brother on them. Documents and communications are hidden from view."

Treehouse's experience gives a glimpse of a solution that could somewhat, if not entirely, replace email. To rethink how it handles internal communications, the company created a Reddit-like forum called Convoy that allows staffers to publicly document conversations and tag other employees. People can proactively check Convoy on their own time and skim the whole forum, plus check their mentions. No more email interruptions from internal connections. No more emails in which you were cc'ed, pushing down missives meant specifically for you.

"When I need information, I pull it. It's not pushed on me all day," Carson says.

Alongside Convoy, Treehouse created a task management system called Flow that publicly displays progress on projects. As team members complete their work, they post status updates such as, "I wireframed a page today and am 25 percent done with my project," which is visible to anyone in the company.

"It gives anyone passing by an instant high-level overview of what's happening with it. ... If you want to know something about it [but aren't working on the project], you just go read about it instead of bothering somebody," Carson says.

But Kevin Fox, the original designer for Gmail who has also worked at Yahoo and Facebook, cautions that what works for Treehouse may not work for every company. "It's dangerous to overgeneralize the workplace," Fox says, adding that in some environments such as a hospital, it's critical that information not fall through the cracks, whereas in a more casual work environment, email is used for a combination of task management and socializing, as in "There are cookies in the break room."

That said, many entrepreneurs and startups view email as the next big problem to be cracked. Startup Asana's tagline says it all: "Teamwork without email," and Huddle has created a successful product combining documents, version control, communications and workflow used by organizations as diverse as Johnson & Johnson, NASA and Beats by Dr. Dre.

"People who are trying to start up companies now grew up in a different time -- email was never their default communication. They grew up with Facebook or MySpace, so they don't use it for social communication. They just look at it as the place where all the crap comes in," Fox says.

While email may be ripe for disruption, many communication alternatives have gained traction without supplanting email. For instance, instant messaging, shared folders, social networking and document collaboration technology have all been "diverting keystrokes away from email into a more appropriate and targeted channel," Schadler notes.

He says that in the next five years, email substitutes may be taken up by small companies and even come to dominate certain departments of large companies, but the challenge for any non-email form of communication will be the fact that its utility will be limited until everyone uses it. So while you may start using a forum to communicate within your company, you'll still probably use email to contact people outside.

In other words, within five years, we may communicate the way Treehouse does now.